Jointed sheet material and methods of forming same



juiy'l3, 1954 Y. G. HURD ETAL JOINTED SHEET MATERIAL AND METHODS OF FORMING SAME Filed 001:. '7, 1950 INVENTORS.

and

HERBER T E. BRA G G n U H N O D R O G K 1 W Y.

PRIOR ART ATTORNEY.

Patented July 13, 1954 UNITED STATES ATENT OFFICE JOINTED SHEET MATERIAL AND METHODS OF FORMING SAME Application October 7, 1950, Serial No. 189,006

23 Claims.

1 This invention relates to jointed sheet material, and to methods for forming the same and is particularly concerned with the formation of substantially unnoticeable seams between the sections of such material.

Large sheets, or screens, of which the motion picture screen is an example, are necessarily built up from strips of material joined, or seamed, edge to edge in order to achieve the requisite size. Heretofore, such seams have been accompanied by such surface distortions as valleys and ribs, and with the ribs extending outwardly of the face of the material and running along the seam. These distortions are due to the outward turning of the radii formed at the turning of the opposed strips where their edges are extended laterally and abutted for seaming.

Improvements in screen materials, most of which materials are formed with backing and facing layers, have resulted in accentuating, rather than reducing the valleys and ribs. At the same time, the effort with respect to motion picture projection has been toward increasing the brightness and rendering it uniform throughout the screen area when viewed over a wide angular field. Hence, even the smallest departure from evenness of screen surface becomes most undesirable.

The instant invention solves the problem by going to the heart of it and eliminating the cause of the distortion. This it does by the formation of special joints between the adjacent strips of screen material, so that the feature of previous joints which caused the valleys and ribs, is eliminated. Instead of turning the full thickness of both pieces of material against each other in the forming of the seam, we have found that an adequate seam can be made merely by joining the backing layers of the material, and terminating the facing layers prior to turning them into the seam. When this is accomplished so that the edges of the facing layers abut and the actual seaming is done in proper aligned relationship with respect to those abutted edges, the joints in the resulting screen surface will be substantially unnoticeable at normal movie screen viewing distance. Obviously, this solves the problem of eliminating the visible ribs which interfere with the angular viewing of motion pictures projected on the screen, but also has application in other fields where a jointed area, having a substantially smooth surface, must be built up.

It is, accordingly, an object of this invention to provide jointed sheet material with substantially unnoticeable seams between the sections thereof.

Another object is to provide methods for forming such materials.

Another object is to provide smooth surface joints between the sections of such material.

A further object is to provide optical projection screens formed out of a plurality of sections of material where the joints between adjacent strips are relatively indistinguishable from the rest of the face of the material.

A still further object is to provide smooth surface joints for joining sections of sheet material formed of layers.

Still further objects are to provide methods for the forming of smooth surfaced optical projection screens, for forming seams between strips of material formed of layers which, though tight, furnish a smooth facing surface, and for forming such joints in simple, economical, fool-proof manner.

Still further objects will in part be obvious, and in part be pointed out as the description of the invention, taken in conjunction with the accompanying drawing, proceeds.

In that drawing:

Figure 1 is a perspective view of a section of jointed sheet material including a seam in accordance with the invention.

Figure 2 is an enlarged fragmentary front elevation of a section of sheet material, as depicted in Figure 1.

Figure 3 is an upside down vertical section of sheet material showing one method of securing strips of such material together.

Figure 4 is a fragmentary vertical section of a strip of sheet material illustrating the severing step of the method.

Figure 5 is a similar view of a composite of two strips, each having one of its layers severed, as in Figure 4, and illustrating the preferred manner of securing.

Figure 6 is a view similar to Figure 5, showing strips prepared for securing in another manner.

Figure 7 is a front elevation of a portion of a sheet formed of strips secured in the Figure 6 manner.

Figure 8 is a fragmentary elevation of adjacent strips of material held together by still a dinerent securing means, and showing those strips in the process of being spread out into sheet form.

Figure 9 is a front elevation of the Fgure 8 fragment showing the sheet on completion of the spreading; and

Figure 10 is a showing of the prior art securing of adjacent strips to form a sheet and illustratine the distortion at the joint as above referred to.

In the description to follow, the product of the invention will, for the sake of simplicity, be considered from the point of view of its applicability to the art of motion picture screens, but it is to be understood that this designation is merely for the purpose of facilitating the description, and is not to be considered in a limiting sense. The invention is equally applicable to all optical proj'ection screens, as well as to any other screen or sheet-like material, where the formation of the substantially unnoticeable seam between strips or panels is desired.

The re ective materials, out of which present motion picture screens are made, are usually made up of several layers employing a base layer of cotton or other fabric as indicated at I in accompanying drawing. This fabric may, if desired, be impregnated with various chemicals in order to control its physical characteristics. One face of the fabric is then coated with one or more layers of a plastic binder carrying appropriate reflective pigments. For simplicity of illustration, these are indicated at 2 in the accompanying drawing, as being just one layer. The face layer 2 is also illustrated as of the same thickness as the base layer l, a condition which is frequently true.

We have found that a substantially unnoticeable joint between strips of such material, as indicated at 3, may be formed by making a fine, accurate, straight out through the coating or face layer of each of the strips to be joined, making sure that the depth of the cut is restricted so as to avoid injury to the fibers of the base cloth. The slits are then opened up by bending the portions of the material remaining beyond the slits downwardly, using the unslit portions of each base layer as the bending section. Thus, as shown in Figure 3, each base layer is bent or hinged around at G and turned partially back on itself as at 5.

The portions of the coating or face layer which are severed from the principal part thereof take the position at 5 on the far side of the portions 5.

The base layer 1 is thin enough that it can be bent back on itself at the line of the slit without any appreciable radius being formed. Thus, when two slitted sections are brought together so that the free ends I of their coating or face layers 2 meet to form the joint 3, the engagement of those free ends will line up with the engagement of what were formerly the inner faces of the base layers at the position where the same are bent around at the opening up of the slit. If then the engaged base portions of two strips are sewn together, through the mated slits, we have found that the coating or face lay ers of the respective strips substantially engage at 3, but remain flat when they do so, and, hence, provide a relatively unnoticeable joint.

One method of securing the bent back base materials together is indicated in Figure 3. Here, a needle 3 is employed at only a slight angle to 4- outer surface 9 of the base layer l. By using this needle, the bent back portions 5 are sewn together in the slit, as indicated at 10. This, however, is a somewhat cumbersome and time-consuming procedure.

A more effective procedure, productive of entirely satisfactory results, is illustrated in Figures 4; and 5. In the Figure 4 showing, the slitting device II is shown as cutting through the coating or face layer 2 of one strip of material generally indicated at (2. This cut must be in a straight line and be accurately positioned wit respect to some portion of the strip, such as the adjacent end [3. The strip [2 so slitted and an exact counterpart thereof, indicated at l4 in Figure 5, are brought together and superimpose with their coated faces toward each other. Their ends I3 are accurately aligned and, consequently, the end faces 7 and the slits l5 are aligned. A sewing needle l6, accurately located with respect to the ends [3, is brought into operation by means of its thread I7, the base layers 1 are sewn together through the slits i5. Thus, when the main portions of the strips are drawn apart about the hinge provided by the sewing and the co1nposite element is spread out into a plane, the end edges of the coating layers 2 formed by the slitting will come around into engagement with each other in the plane 3, as shown in Figures 1 and 2. By securing the strips together in this manner, a complete motion picture screen or other large flat sheet can be built up without the joints or seams between the strips introducing any appreciable variation from a continuous plane into the composite outer face.

A modified manner of securing is illustrated in Figures 6 and '7. In Figure 6, two strips, l8 and 19, after having been slitted in the Figure 4 manner, have the small severed section of coating or face layer between the slit and the adjacent end stripped 011 of the base layer. Thin layers of adhesive 20 and 2| are applied in place of the stripped off coating. The sheets are then laid with their coated surfaces face to face with the ends 22 thereof in alignment. Here, however, instead of securing the strips together by sewing, such is done by separating the sheets, drawing them around to engage their end surfaces 22 and then engaging the adhesive layers 26 and 2|. The adhesive layers 20 and 2i when suitably pressed together become a composite mass, as seen at 23 in Figure '7. The ends 2 2 and 25 are thus secured together which engages the ends 22 in the plane 26.

A good grade of glue, or other strong adhesive. may be employed keeping in mind that the coating layer should be stripped off beyond the slit so that the adhesive engages the base layer. Double faced adhesive tape may also be employed, but in such case the strips should also be stitched for really effective holding.

Another alternative securing arrangement is shown in Figures 8 and 9. Here, the strips 21 and 28 are again slitted, as in Figures 4 and 5, and are placed in opposed relationship. The securing together of the strips is effected by means of staples 29. These staples pass through both the strips, as in the case of the thread used in sewing, and do so in exactly the same location as the thread, that is, through the aligned slits. When, as shown in Figure 9, the main portions 2? and 28 of the strips have been separated and drawn out into a fiat plane, a relatively unnoticeable joint will result at the common plane 30.

It is to be appreciated that certain changes may be made in carrying out the above-method and certain modificationsimay be made-in the above article which embody the invention without departing from thescope of that invention. It is thus intended that all matter-contained in the above description, or shownin the accompanying drawing, shall be-interpreted as illustrative, and not in alimiting sense.

Having described our invention, whatwe claim as new and desire tosecure byL-etters Patent-is:

1. The -method-of forminga seam between strips of laminated sheet'material'formedof a plurality of adhered layers which comprises, sev- I ering one portion of the face layerzof :eacha strip of material from: another :portion thereof, .WlnTle T stopping said severing .at the upperisurfaceof the next layer, securing said-stripsof material together by means of .thezunsevered layer seating one end face of each of said severed layers in alignment.

2. Those steps in themethod of securing two strips of adheredlayersheet material together to provide a substantially smooth surface-across the seam between them, which comprise, severing one portion of the face layer of each: of said strips from another portion thereof on a straight line adjacent an edge of each strip, engaging the portions of said strips between said straight line and said edge with the severed faces thereof in face to face relation, and securing the unsevered layers of said strips together.

3. Those steps in the-method of securing two strips of adhered layer sheet material together to provide a substantially smooth surface across the seam between them whichcomprise, cutting through the face layer of each of said strips on a straight line adjacent an edge thereof and stopping said cuttingat the-inner surface of said face layer, placing said strips in face to face relation with said face layers innermost and the lines of cut of the opposed strips in alignment, passing securing means through the uncut layers and through said out and separating the main portions of said strips from each oth r by bending the strips about the secured positions thereof and extending them into asingle plane.

The method of securing strips of adhered layer sheet-like material together in order to produce a substantially smooth, plane'surface' extending across the same-which comprises, cutting through the face layer of each strip along a line adjacent an edge of the strip to form a slit therein, facing portions-of the cutlayers'of said strips between each slit and the adjacent edge of said strips, securing said faced portions ofsaid strips together by sewing through the opposed slits and through the material in bacl; of the same and locatingthe main portions of the strips substantially in a plane by abutting the end faces of the cut layers of themain-portions of the strip.

5. A joint for securing together sheets of coated material to provide a smooth surface'on one face thereof which comprises, twostrips of such material having the coating thereof terminated-in a straight end face, and having portions of said material extending beyond said straight end face,- said straight end faces-of said strips being engaged in abutting relationship, extending portions of said material extending beyond the zone of abutment of said end faces, and being turned away therefrom, and-meansholding said turned away portions together to maintain saidabutted relationship of-said end faces.

6. A joint for securing together sheets of coated material to provide a smooth surface on'the" coated: face-thereof-which comprises, a plurality of strips of such material eachhaving the coating layer :thereof terminated in a straight end face adjacent one edge of the strip and having a portion of such strip extending beyond saidend face, said end faces of said coating layers engaging in abutting relationship,said'extending portions be ing turned away from, the 1 zone of abutment of saidfend faces andthreadspassed through said. turned away portionsat a. position closely underlying said zone of abutment, said. threads drawing said turned away-portions tightly together to maintain said end facesin tight abutting relationship.

7. A jointedsheet presenting a substantially flat continuous outer surface which comprises, a plurality of. strips-of sheet material formed of layers having said layers secured together throughout, said strips being laid out in side by side relation, the face layers'of said stripsabutting in edge to edge relation and thebase layers of said strips havingportions. thereof secured together by independent securing means to tain said facelayers in said abuttedrelationship.

8. A jointedsheet presenting a substantially flat continuous outer surface comprising, a plurality of strips of sheet material formed of layers having said layers secured together throughout, said strips being laid out in side by side relation, the face layers of said strips abutting-in edge to edge relation and the base layers of said strips extending away from the Zone of abutment of said face layers and having portions thereof secured together closely-adjacent said Zone-of 'ment to retain said face layers in said abutted of said main portion, said end faces of two adjacent elements being seated against each other in abutting relationship, and securing means engaging the extending portions-of each element and securing the same together for maintaining said'abutting relationship of said end faces.

10. A jointed sheet formed of elements of stri, material, said material being formed of a pinrality of layers with said layers secured together throughout, each element having the face layer thereof terminated in a straight end face spaced from the adjacentedge-of said element, said end faces of said face layers of two adjacent elements being seated againsteach' other in abutting relationshipand means for securing the portions of said elements between said end faces and said adjacent edges together to maintain said abutting relationship of said end faces.

11. A substantially fiat surfaced sheet formed of strips of sheet material,- said material being formed-of layers with said layers secured together throughout the strips'which comprises, a pair of said strips laid outin side by side relation to form a continuous flat surface, one of the layers of one of said strips being provided with an face, the comparable layer of the other of strips also being provided with an end face, said end faces-being abutted in face to face relationship to form a butt joint, the remaining layers of said strips being turned away-fromsaicl' butt joint in face" to face" relation, andnieans for securing said turned away layers together to maintain said butt joint in even contact.

12. In a motion picture screen, a pair of strips of sheet material formed of layers with said layers being secured together throughout said strips, said strips being laid out in side by side relation to form a continuous fiat surface, one of the layers of one of said strips being provided with an end face, the comparable layer of the other of said strips also being provided with an end face, said end faces being abutted together in face to face relationship to form a butt joint, the remaining layers of material of said strips beyond said end faces being turned away from said butt joint into face to face relationship, and means passing through said turned away layers at substantially the point of face contact for securing said strips together tomaintain said butt joint in even contact.

13. Those steps in the method of securing together two strips of material formed of adhered layers to provide a substantially smooth surface across the seam between them which comprises, cutting through the face layer of each of said strips on a straight line adjacent an edge of said strips, engaging the portions of said strips between said straight line and said edge with said face layers in face to face relation, and passing securing means through the unsevered layers of said strips and through the slit resulting from the cutting of said face layer.

14. The method of securing two strips of adhered layer material together which comprises, cutting through the face layer of each of said strips adjacent an end of each of said strips, opening the slits formed by said cutting by bending the material between said slits and the said adjacent edge of said strip away from said face layer, and securing said bent portions of said material together.

15. The method of forming a jointed motion icture screen out of sheet material, including a base layer and a face layer adhered thereto, with a smooth surface across the seams between the elements thereof, which comprises, cutting through said face layers of two elements of said material on a straight line adjacent an edge thereof and stopping said out at said base layer, placing said elements in face to face relation with the cut layers against each other and with the cuts in each element in alignment, sewing said elements together by passing a thread through the unsevered base layers and through the cuts in said face layers, separating the main portions of the elements and hinging them about said sewing to spread said sections out into a single plane with the opposed cut edges of said face layers in abutting relation.

16. A jointed sheet formed of elements of strip material, said strip material being formed in layers and having the layers thereof secured together throughout, each of said elements having their face layers separated along a straight line to divide each of said elements into a main portion and an extending portion and to form an end face on each of said face layers at the end of each of said main portions, and exposing the base layers of said material, said end faces of two adjacent elements being seated against each other in abutting relationship and securing neans passing through the exposed portions of said base layers to secure said end faces in abutting relationship.

l'l. A jointed sheet formed of elements of strip material, said material being formed of layers secured together throughout the strip, each of said elements having their face layers separated along a straight line to divide each of said elements into a main portion and an extending portion and to form an end face on each of said face layers at the end of each of said main portions, said end faces of two adjacent elements being seated against each other in abutting relationship, said extending portion of each element extending away from the zone of abutment of said end faces and having sections engaged in face to face relation, said sections being secured together to maintain said end faces in said abutting relationship.

18. A jointed sheet formed of elements of strip material, said material being formed of layers secured together throughout the strip, each of said elements having their face layers separated along a straight line to divide each of said elements into a main portion and an extending portion and to form an end face on each of said face layers at the end of each of said main portions, said end faces of two adjacent elements being seated against each other in abutting relationship, said extending portion of each element extending away from the zone of abutment of said end faces and having sections engaged in face to face relation, and securing means passed through said extending portions adjacent said line of separation to maintain said end faces isaid abutting relationship.

19. A jointed sheet formed of elements of strip material, said material being formed of layers secured together throughout the strip, each of said elements having their face layers separated along a straight line to divide each of said elements into a main portion and an extending portion and to form an end face on each of said face layers at the end of each of said main portions, said end faces of two adjacent elements being seated against each other in abutting relationship, said extending portion of each element extending away from the zone of abutment of said end faces and having sections engaged in face to face relation, with an adhesive element ther between, said adhesive element serving to secure said sections together.

20. The method of securing together a pair of strips of sheet material, formed of a plurality of adhered layers, which comprises, dividing each strip into two portions by severing one section of one of said layers from another section thereof, abutting the end faces of said one tion of each of said strips and maintaining said abutting relationship by securing together the portions of said strips to which said other sections are adhered.

21. The method of securing together a pair of strips of sheet material, formed of a plurality of adhered layers, which comprises, dividing each strip into two portions by severing one section of one of said layers from another section thereof, and stopping said severing short of the next layer, abutting the end faces of said one section sec- " of each of said strips and maintaining said abutting relationship by securing together the por tions of said strips to which said other sections are adhered.

22. The method of securing together a pair of strips of sheet material, formed of a plurality of adhered layers, which comprises, dividing each strip into two portions by severing one section of one of said layers from another section thereof, along a straight line, abutting the end faces of said one section of each of said strips and maintaining said abutting relationship by securing together the portions of said strips to which said other sections are adhered.

23. The method of securing together a pair of strip-s of sheet material formed of a plurality of adhered layers which comprises, severing one portion of the face layer of each strip from another portion thereof along a straight line, securing together the portions of said strips at one side of the line of severance corresponding to said other portion of said face layer and bringing together the end faces of said one portion of said face layer to form a substantially smooth faced surface.

References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Terry Apr. 20, Alt et al May 3, Turner Oct. 27, Lustberg Apr. 26, Pitrnan May 24:, Walker Sept. '7, Welch July 25, Merrill Apr. 3, Bennett Apr. 24, 

1. THE METHOD OF FORMING A SEAM BETWEEN STRIPS OF LAMINATED SHEET MATERIAL FORMED OF A PLURALITY OF ADHERED LAYERS WHICH COMPRISES, SEVERING ONE PORTION OF THE FACE LAYER OF EACH STRIP OF MATERIAL FROM ANOTHER PORTION THEREOF, WHILE STOPPING SAID SEVERING AT THE UPPER SURFACE OF THE NEXT LAYER, SECURING SAID STRIPS OF MATERIAL TOGETHER BY MEANS OF THE UNSERVED LAYER AND SEATING ONE END FACE OF EACH OF SAID SEVERED LAYERS IN ALIGNMENT.
 7. A JOINTED SHEET PRESENTING A SUBSTANTIALLY FLAT CONTINUOUS OUTER SURFACE WHICH COMPRISES, A PLURALITY OF STRIPS OF SHEET MATERIAL FORMED OF LAYERS HAVING SAID LAYERS SECURED TOGETHER THROUGHOUT, SAID STRIPS BEING LAID OUT IN SIDE BY SIDE RELATION, THE FACE LAYERS OF SAID STRIPS ABUTTING IN EDGE TO EDGE RELATION AND BASE LAYERS OF SAID STRIPS HAVING PORTIONS THEREOF SECURED TOGETHER BY INDEPENDENT SECURING MEANS TO RETAIN SAID FACE LAYERS IN SAID ABUTTED RELATIONSHIP. 